Apparatus for removing section of covering from plastics-covered wire

ABSTRACT

A mechanism for removal of sections of covering from intermediate regions along a wire covered with pliable plastics material comprising two heads each involving an H-like array of members of which each outer member is a cutting blade, the blades being so arranged that when the heads are brought into operative relationship with the covered wire the blades partially pierce the covering at two axially spaced locations and the heads are provided with blade deflecting means which when actuated deflect the blades of each head laterally away from each other to complete the severance from the body of the wire covering of that section of the covering located between the blades.

United States Patent Mackay [54] APPARATUS FOR REMOVING SECTION OF COVERING FROM PLASTICS-COVERED WIRE [72] Inventor: Ronald George Mackay, Liverpool, En-

gland Plessey Handel und Investments A.G., Zug, Switzerland [22] Filed: Dec.4, 1970 [21] Appl.No.: 95,]69

[73] Assignee:

[30] Foreign Application Priorlty'Data Dec. 24, 1969 Great Britain ..62,826/69 [52] U.S. Cl ..29/427, 8 U95 1 83/924, 225/96 [51] Int. Cl. ..B23p 19/02, H02g 1/12 [58] Field of Search ..81/9.51; 29/427; 83/924; 225/96 [451 Apr. 25, 1972 [56] References Cited UNITED STATES PATENTS 3,364,801 l/l968 Johnston ..8l/9.5l 3,527,124 9/1970 Ullman ....8l/9.51 2,521,688 9/1950 Cataldo et al... ....8l/9.5l 3,309,947 3/1967 Denney ..8 H951 Primary Examiner-James L. Jones, Jr. Attorney-Blum, Moscovitz, Friedman & Kaplan [57] ABSTRACT A mechanism for removal of sections of covering from inter- 'mediate regions along a wire covered with pliable plastics material comprising-two heads each involving an l-I-like array of members of which each outer member is a cutting blade, the blades being so arranged that when the heads are brought into operative relationship with the covered wire the blades partially pierce the covering at two axially spaced locations 'and the heads are provided with blade deflecting means which when actuated deflect the blades of each head laterally away from each other to complete the severance from the body of the wire covering of that section of the covering located between the blades.

6 Claims,v l3 Drawing Figures PATEHTEDAPR 2 s 4972 3, 6 57, 7 9 5 SHEET 2 BF 3 APPARATUS FOR REMOVING SECTION OF COVERING FROM PLASTICS-COVERED WIRE The present invention relates to a method and apparatus for removing sections of covering from plastics-covered wires.

A vast quantity of plastics-covered wire is used in the telecommunications industrytypically in the interconnection of components incorporated in functional units such as stripmounted groups of relays, jack-in relay sets and selector switches. The wire used for this purpose is of tinned-copper of say 23 or 25 S.W.G. (standard wire gauge) and the covering is of pliable thermoplastic material generally polyvinylchloride (p.v.c.). The removal of a section of p.v.c. covering from an end of a wire, insulated in this manner to expose a region for making a wrapped connection to a terminal tag, offers no great problem. One well-known technique to to partially sever or nick the insulation at an appropriate distance from the end of the wire and to withdraw the unwanted end-section of covering as a tube. This is already done rapidly and elegantly by automatic machines which are adapted to draw the insulated wire from a reel, to cut the wire into predetermined equal lengths and to remove a prescribed section of insulation from each end of each such length.

The problem of removing a section of covering from one or more intermediate points along a wire insulated with p.v.c. is not readily overcome. Indeed methods have been considered which involve the raising or lowering of the environmental temperature of each location, from which covering is be be removed, to change the nature of the insulation material. According to a first method the raising of the temperature to a point at which a section of covering is molten or semi-molten would enable the insulation to be removed or drawn-back by mechanical means. In the second of the considered methods, a very substantial reduction in temperature is required, over the appropriate region, to so change the state of the insulation material as to permit it to be shattered by impact.

The present invention has in view an improved method for removing sections of covering from plastics-covered wire and also apparatus of simple economic and reliable construction for carrying out the method without the necessity for subjecting the sections to be removed to special environmental conditions as described above.

According to the present invention there is provided a method for the removal of a section of covering from an intermediate region of a wire covered with pliable plastics material in which the section of covering is severed circumferentially from the body of the wire covering at two spaced locations by automatic means and is severed lengthwise and thereafter the severed section is peeled off as by drawing the wire along a path involving an abrupt change of direction which is such as to allow the wire to emerge progressively through the lengthwise severance in the section of covering.

The present inventionalso provides apparatus for cutting sections of pliable plastics wire covering material at intermediate positions along a wire covered with said material comprising two heads each including two spaced cutting blades the blades of the two heads being so arranged that when the heads are brought into operative relationship with the covered wire lying in a predetermined path between them said cutting blades partially pierce the covering circumferentially at two spaced locations along the covered wire and the heads are provided with blade deflecting means which when actuated deflect the two cutting blades of each head away from each other in the axial direction of the wire to complete severence of that section of the wire covering between the heads from the remainder of said wire covering and in which means is provided for severing the section of wire covering in the axial direction to permit of its removal from the wire. The two spaced cutting blades of each head may constitute the outer members of an I-I-shaped cutting head.

The central limbs of the I-I-shaped heads may comprise additional cutting blades which when the heads are brought into operative relationship with the covered wire co-operate to effect partial piercing of the covering from opposite directions over substantially the whole length of the section of wire covering to be removed and in which the blade deflecting means when actuated is operative to deflect the additional blades laterally of the wire and in the same direction to complete the severance of said section of covering into two substantially semi-cylindrical sections.

Alternatively, the central limbs of the I-I-shaped heads may comprise bars which when the heads are brought into operative relationship with the covered wire effect pinching of the section of wire covering to be removed an additional blade intermediate the two heads being operative during the pinching function and whilst the spaced cutting blades are deflected to produce a cut through the covering over the length of said section in the same plane as the axis of the wire, the pinching function being so performed as to distort the section of covering to permit the additional blade to cut through the covering without touching the wire itself. The severed section of covering may be peeled off by a device which comprises means enabling the wire to be drawn along a path involving an abrupt change of direction which is such as to allow the wire to emerge from the severed section of covering in a progressive way along the lengthwise cut in the section of covering.

The invention will be better understood from the following description of the preferred methods of carrying it into effect which should be read in conjunction with the accompanying drawings of which FIGS. 1, 2, 3a, 3b, 4, 5a and 5b relate to one embodiment, whereas FIGS. 6a, 6b, 7a, 7b, 8 and 9 relate to another embodiment. Of the drawings FIGS. 1 and 2 are partial general views of two identical devices involved in a first proposed mechanism, the two views being appropriate to the dormant and fully operative states respectively of the mechanism;

FIGS. 3a and 3b are views of one portion of that mechanism in a first state of a sequence of states involved in the removal of a section of covering from a wire; whereas FIG. 4 is a view of that portion of the mechanism in a second state; and

FIGS. 5a and 5b are views appertaining to a third and fully operative state of the same portion of the mechanism.

FIGS. 6a and 6b are part views of a modified form of the mechanism the relevant parts being in the dormant state; whereas FIGS. 7a and 7b are corresponding views with the mechanism in the operative state;

FIG. 8 is an enlarged representation of a portion of FIG. 7b;

FIG. 9 shows details of that portion of the modified mechanism concerned with the peeling-off of a section of wire-covering.

Considering FIG. 1, the mechanism involves two identical devices, conveniently to be referred to as heads. The one at the left, now to be described in some detail is pictorially depicted as having a portion of blades 12 and 11 broken away to assist in the appreciation of certain otherwise obscured details. The typical (left-hand) head comprises a body of 10 of accurately machined tool-steel with a base portion of dovetail form which is slideably located in the complimentary groove or runner of a bed (not shown); the runner serving both stripping heads to permit lengthwise slideable movements of the heads without any perceptible lateral play. The body has an integral horizontal platform portion 19 narrower than but symmetrically disposed with respect to the rest of the body. The platfonn, incorporating the transverse slot 20, terminates in the same plane as the front face of the body, and extends between the L-shaped upstanding walls 14 and 15 formed integrally with the body.

The typical head carries three accurately-positioned blade members ll, 12 and 13 which present a symmetrical I-I-like array outwardly of the front face of the body 10. The flat vertical blades 12 and 13 are located in an appropriate side-channel formed by wall 14 or 15 and each about the relevant edge of platform 19 which therefore acts as a backstop for each of said blades. Each of blades 12 and 13 is secured by clamping screws such as 16 leaving that portion which is not embraced by the side channel available to be deflected outwardly, i.e., away from each other.

The front edges of blades 12 and 13 are aligned with each other, and each has a central notch 17 constituting a counterbored chamfered cutting edge coinciding with the inner face of the particular blade, the size of the notch is determined by the size of the wire to be worked upon and the thickness of its covering (p.v.c.), the requirement being that when it is appropriately urged against the covered wire it shall pierce the covering to an adequate depth, and to an extent approaching half its circumference, without touching or in any way damaging the wire. In the example (shown more clearly by the encircled enlargement) the notch is substantially semi-circular but other configurations may be employed.

The third blade 11 of the typical stripping head has its wide portion snugly located between blades 12 and 13; the narrower portion being located between walls 14 and 15. Blade 1 1 is mounted upon the previously-mentioned platform and is clamped to the body in the region between the walls (by menas not shown) leaving the wide portion, with its chisel-like edge 18, available for deflection upwardly.

The cutting edge 18 of blade 11, extending beyond the front face of the body, is aligned with the root of the cutting-edge of notch 17 of blade 12 and the root of the corresponding cutting-edge of blade 13. The elongated cutting-edge 18, when appropriately applied to the covered wire 24, provides for the longitudinal piercing of the covering to an adequate depth over substantially the whole of the region defined by blades 12 and 13, again without touching or in any way damaging the wire itself.

The means for deflecting the three blades 11, 12 and 13 of the cutting head is located in a trough in the body base, at a point immediately below the transverse slot 20. Said means comprising a T-shaped member 21, say of tool-steel, and two steel balls such as 22. Steel rollers of cylindrical form may be used instead of the balls. The configuration and disposition of the blade-deflecting means is clearly indicated in FIGS. 3a and 3b. However the vertical limb 23 of the T-shaped member takes the form of a rod which passes through a hole in the base of the body where lower portion of the rod is exposed so as to enable the member to be pushed upwardly.

An identical means for deflecting blades 11, 12' and 13 of I the right-hand head is incorporated in the latter.

As already mentioned the two heads are identical and are each capable of being moved towards each other along a bed upon which they are mounted. FIGS. 1 and 2 represent the heads at their outer and inner limits of movement respectively. Motivation of the heads is accomplished by a known form of reciprocating mechanism (not shown). I

With the stripping heads retracted as shown in FIG. 1, the p.v.c. covered wire 24 is pulled from a reel or the like along a path midway between the heads; suitable guides (not shown) being provided to accurately define the path in the vicinity of .the head which ensures that.the horizontal cutting edges 18 of the two heads are substantially co-planar with the axis of the wire.

The wire-pulling mechanism (not shown) is stopped to leave that section of wire, from which the covering is to be removed, between the cutting-blade arrays of the heads. The heads are then driven to their inner limits as represented in FIG. 2, although none of the blades are yet deflected. At this position corresponding vertical blades of the two heads are just touching endwise or are barely perceptably clear of each other. At this stage the cutting-notches of each pair of opposing vertical blades is operative to pierce the covering over two opposing arcs (approaching semi-circles); the piercing being halted just short of the wire itself. Obviously these circumferential cutting operations, defining the length of covering to be stripped, leave that length still attached to the body of the covering by shreads or webs which require to be broken.

Concurrently with the circumferential cutting operation I the, cutting edges 18 of the heads produce opposing longitudinal cuts in the section of covering to depths approaching the thickness of the covering.

The various concurrent piercing operations define two semi-cylindrical regions constituting the section of covering to be removed but which are still attached to each other and to the body of the covering by webs which require to be broken to complete the severance of the two regions of the section of covering.

With the heads now at their inner limit positions as represented in FIG. 2. the need now arises to deflect the six blades 11, 11, 12, 12 13 and 13 in the manner depicted therein, i.e., the requirement is to deflect the pairs of blades 12/12 and 13/13 away from each and then to deflect blades 11 and 11 upwardly. These operations are to jointly bring about the complete severance of the defined semi-cylindrical regions of covering from each other and from the covering which is to remain.

Prior to any deflection of the blades, the section of insulation is gripped between two upper and lower pressure pads 25 and 26 which are moved, downwards and upwards respectively, into position by a suitable driving means (not shown). The pressure pads, although depicted in FIGS. 3b and 5b, are omitted from the other illustrations for simplicity, but it may be taken that the lower pad has its upper surface grooved for locating the defined section of covered wire when the thinner extremity of the upper pad is exerting pressure. Both pads ex tend the length, or slightly less than the length, of the covering to be removed.

FIGS. 3:: and 3b represent the three blades of one of the heads in relation to the means for deflecting them; FIG. 3!: being a crosssectional view in the direction of the arrows A- A of FIG. 3a (wire omitted) and incorporating a portion of the platform 19. In both the illustrations the T-shaped member 21 is in its lowermost, and therefore unactuated, position which still obtains when the heads first reach their inner limits of stroke. At this juncture the initial piercing of the covering has been effected as described and the section of covered wire is gripped between the pressure pads. Upward movement of the T-shaped member now proceeds under control of an activating device (not shown) operative on the foot of the rod 23. The steel balls 22 and 22, previously engaging points in the upper regions of the steeply-rising faces 27 and 27 respectively and being contained in transverse slot 20 (FIG. 1) by an appropriate pair of blades (11/12 or 11/13), are now acted upon by said steeply-rising faces to urge blades 12 and 13 away from each other.

This action takes place concurrently with respect to both heads so that blades 12 and 12 are deflected leftwards and blades 13 and 13 are deflected rightwards by the outward movement of each ball. Sincethe wire-covering is still engaged in the vicinity of the blade notches,'the covering outwardly of the portion to be removed is compressed lengthwise. This effects rupturing of the shreads hitherto linking said portion to the main body of the covering. The action is assisted by the retaining efi'ects of the pressure pads 25 and 26. 7

When the balls are engaged by the respective horizontal shoulder of member 21 (as shown in FIG. 4.) the outward movement of the particular pair of vertical blades is completed. This will take place concurrently in both heads.

For the continuing upward movement of the typical T- shaped member the balls are entrained with it and the pertinent blade 11 is deflected upwardlyby the deflecting means. FIGS. 5a and 5b (corresponding to FIGS. 3a and 3b respectively) show the state appertaining on completion of the upward stroke of the blade deflecting means. In this'state, with the vertical blades still fully deflected, the horizontal blade has .now reached maximum deflection. It should be pointed out that the latter blade, in conjunction with the concurrently-actuated corresponding horizontal blade of the other head and the upper pressure pad, has now had the effect of severing the remaining shreads which hitherto linked together the semicylindrical sections of covering.

At this juncture the blade-deflecting means of the two heads are retracted to allow the blades. torelax, and the two heads and the pressure pads are withdrawn. During and/or subsequent to these functions a stream of air or other suitable fluid is directed upon the semi-cylindrical sections of covering so as to complete their removal as waste material.

Having removed the section of covering, the wire is advanced a required distance in readiness for the whole stripping sequence to be performed again. The whole process is repetitive in effecting the stripping of cover-sections from a length of wire which is eventually to be used by an operator in the wiring-up of connection tags in an electromagnetic relay set or the like; each bared section of wire being sufficient to provide a wrap-around connection with respect to a tag preparatory to soldering. A single wiring run may involve connecting two, three or more variably-spaced tags and may be followed by other runs again involving two, three or more tags. It is envisaged that a mechanism of the kind described could be employed to strip sections of covering from a single length of wire to enable the appropriate pattern of wiring to be effected. The distances between successive bared sections of wire will be determined by the layout of the tags involved in each run. Since the operator will be required to cut the wire at the midpoint of a bared section intermediate each run for the purpose of making two connections (one being to the last tag of one run and the other being the first tag of another run) it will be desirable to increase the length of the relevant stripped portion. This requirement is readily met by the mode of utilisation of the stripping mechanism. Accordinglyafter a section of covering has been removed in the manner already described, the wire is advanced by an amount which is not greater that the distance between the vertical blades, whereupon the stripping operations are again performed.

It is envisaged that the stripping mechanism and its associated driving devices, together with means for advancing the wire, would be controlled by an electronic process control unit programmed in accordance with the required pattern of spacings between stripped regions and the lengths of those regions.

The modified form of mechanism, to which FIGS. 6a, 6b, 7b, 8 and 9 relate, will now be considered. In this mechanism, the body of each head is substantially as before, and the form of the flexible vertical blades 12/13 and 12/13 is retained; each blade having a cutting notch 17 of the kind already described. However the horizontal blade of each l-Hike array is replaced by a substantial and inflexible bar 29 or 29. The upper and lower pressure pads 25 and 26 are dispensed with, but a fixed central block 30 and an upper chisel-like steel blade member 31 are incorporated.

FIGS. 6a and 6b relate to the dormant state of mechanism whereat the two heads are retracted. Accordingly in FIG. 6a (from which the wire is omitted for simplicity) the T-shaped blade-deflecting member 21, operable by its rod 23, is in its lowermost position so that the vertical blades 12 and 13 of the particular head are relaxed and therefore in abutment with the sides of bar 29 and the platform supporting that bar. Similar considerations apply to the other identical head, as can be deduced from FIG. 6b which is a cross sectional view in the direction of arrow BB of FIG. 6a but embracing features of both heads. The T-shaped members 21/21 and associated balls or rollers are identical with the corresponding items of the first-described arrangement but the stroke of each member is reduced since bars 29 and 29 are not to be deflected.

The fixed central block 30 located snugly between vertical blades of both heads (when the blades are relaxed) has a semicircular groove in its upper surface to constitute a track which snugly embraces the covered wire 24. This groove is equidistant between the two l-Hike arrays formed by the vertical blades and bars 29 and 29. Moreover the cutting-edge of blade member 31 is vertically aligned with the axis of this groove and therefore with the axis of the wire. It is also to be noted from FIG. 6a that the blade member 31 is symmetrically located with respect to blades 12 and 13 of the particular head and indeed is slightly broader than the distance between the opposing faces of those blades. Blade member 31 has the same relationship with the vertical blades of the other head.

It is to be noted, from FIG. 6b, that bars 29 and 29 ride, at their inner ends, upon the top flat surface of the fixed central block. The bars are each so secured with respect to body of the appropriate head that the innermost vertical edge is substantially aligned with the root of the notch 17 in each of the vertical blades of particular H-like array.

With lower half of the p.v.c.-covered wire contained in the groove, the two heads are driven, along their common bed, to their inner positions, as shown in FIG. 7b, and defined by suitable stops (not shown). In this situation corresponding vertical blades of each head are just touching or are barely perceptably clear of each other and each pair of opposing vertical blades pierce the covering over two opposing arcs. As in the previous example the piercing is halted just short of the wire itself. Again the circumferential piercing operations leave the unwanted length of covering still attached to the body of the covering by shreads or webs. At this time also, the inner faces of bars 29 and 29 are brought to such a position as would cause the upper exposed half-section of the covered wire to be pinched between them. The effect of the pinching is demonstrated by FIG. 8 in that upper region of covering is distorted and lifted clear of the wire itself.

At this juncture the T-shaped members 21 and 21 are raised until they abut, or are just clear of, bar 29 and 29 respectively. During this upward movement transverse outward movements are imparted to the vertical blades of the two heads by the actions of the steel balls or rollers in co-operation with the sloping faces of said members. This completes severance of the required tubular section from the body of the covering.

With the vertical blades, 12/13 and the like, still deflected, pneumatic or other actuating means are operative on blade member 31 to move it downwardly into the region between the pair of blades of each head, to a position (represented in FIGS. 7a, 7b and 8) so that it produces a single lengthwise cut through the whole of that portion of covering which has been lifted clear of the wire. A stop (not shown) prevents excessive downwards movement of the blade member 31, and so it is ensured that the cutting edge, although passing through the covering does not engage the central conductor.

The situation now is that the unwanted tubular section is completely detached from the remainder of the covering and has a single lengthwise cut extending through it.

The blade member 31 is now retracted and this is followed by the lowering of members 21 and 21 to release the deflected vertical blades. Subsequently the heads are moved away from each other and ultimately the wire drawn along its prescribed path in readiness for another section'of its covering to be worked upon by the various blades.

As the wire is withdrawn from that region of the machine at which severance and lengthwise cutting of each unwanted section of covering is effected, it is pulled, as shown in FIG. 9, through a hole in a guide member 33. The wire is guided over a small diameter roller 34 having its axis at right engles to, and slightly below, the axis of the hole through member 33. The wire also drawn over the larger roller 35 which has its axis somewhat higher than that of roller 34. As a result of the disposition of the two rollers, it is apparent that the wire is subjected to an abrupt change of direction as it passes round roller 34.

A typical section of covering 38, defined by circumferential cuts at points 39 and 40, is represented as having been partially removed in FIG. 8. The section of covering, like all corresponding sections, passes under roller 34 with its lengthwise slot (previously produced by blade member 31) uppermost, i.e., against the roller. As the leading end 40 of the typical section 38 meets the abrupt change of direction being followed by the wire, the covering tends to continue along the line of approach to the roller 34. As a result of this the lengthwise slot in the covering section opens and therefore the unwanted section progressively peels itself from the wire and becomes completely detached from wire as the following end 39 of the section passes beyond roller 34. The peeling action may be assisted by the spring member 36 which is secured on the support 37; the nose portion at the free end of member 36 serving to deflect the unwanted section downwardly.

What we claim is:

1. Apparatus for cutting sections of pliable plastics wire covering material at intermediate positions along a wire covered with said meterial, comprising two heads each including two spaced cutting blades the blades of the two heads being so arranged that when the heads are brought into operative relationship with the covered wire lying in a predetermined path between them said cutting blades partially pierce the covering circumferentially at two spaced locations along the covered wire and the heads are provided with bladedeflecting means which when actuated deflect the two said cutting blades of each head away from each other in the axial direction of the wire to complete severance of that section of the wire-covering between the heads from the remainder of said wire-covering and in which means is provided for severing the section of wire covering in the axial direction to permit removal thereof from the wire.

*2. Apparatus as claimed in claim 1, in which the two spaced cutting blades of each head constitute the outer members of an H-shaped cutting head.

3. Apparatus as claimed in claim 2, in which the central limbs of the H-shaped heads comprise additional cutting blades which when the heads are brought into operative relationship with the covered wire co-op'erate to effect partial piercing of the covering from opposite directions over substantially the whole length of the section of wire-covering to be removed and in which the said blade-deflecting means when actuated is operative to deflect the additional blades laterally of the wire and in the same direction to complete the severance of said section of covering into two substantially semi-cylindrical sections.

4. Apparatus as claimed in claim 2, in which the central limbs of the H-shaped heads comprise bars which, when the heads are brought into operative relationship with the covered wire, effect pinching of the section of wire-covering to be removed, an additional blade intermediate the two heads being operative during the pinching function and whilst the spaced cutting blades are deflected to produce a cut through the covering over the length of said section in the same plane as the axis of the wire, the pinching function being so performed as to distort the section of covering to permit the additional blade to cut through the covering without touching the wire itself.

5. Apparatus as claimed in claim 4, in which a device is provided for peeling off the severed section of covering, said device comprising means enabling the wire to be drawn along a path involving an abrupt change of direction which is such as to allow the wire to emerge progressively outwards through the lengthwise cut in the section of covering.

6. A method for the removal of a section of covering from an intennediate region of a wire covered with pliable plastics material in which the section of covering is severed circumferentially from the body of the wire-covering at two spaced locations by automatic cutting means and is severed lengthwise and thereafter the severed section is peeled off as by drawing the wire along a path involving an abrupt change of direction which is such as to allow the wire to emerge progressively outwards through the lengthwise severance in the section of covering.

* l t I! 

1. Apparatus for cutting sections of pliable plastics wire covering material at intermediate positions along a wire covered with said meterial, comprising two heads each including two spaced cutting blades the blades of the two heads being so arranged that when the heads are brought into operative relationship with the covered wire lying in a predetermined path between them said cutting blades partially pierce the covering circumferentially at two spaced locations along the covered wire and the heads are provided with blade-deflecting means which when actuated deflect the two said cutting Blades of each head away from each other in the axial direction of the wire to complete severance of that section of the wire-covering between the heads from the remainder of said wire-covering and in which means is provided for severing the section of wire covering in the axial direction to permit removal thereof from the wire.
 2. Apparatus as claimed in claim 1, in which the two spaced cutting blades of each head constitute the outer members of an H-shaped cutting head.
 3. Apparatus as claimed in claim 2, in which the central limbs of the H-shaped heads comprise additional cutting blades which when the heads are brought into operative relationship with the covered wire co-operate to effect partial piercing of the covering from opposite directions over substantially the whole length of the section of wire-covering to be removed and in which the said blade-deflecting means when actuated is operative to deflect the additional blades laterally of the wire and in the same direction to complete the severance of said section of covering into two substantially semi-cylindrical sections.
 4. Apparatus as claimed in claim 2, in which the central limbs of the H-shaped heads comprise bars which, when the heads are brought into operative relationship with the covered wire, effect pinching of the section of wire-covering to be removed, an additional blade intermediate the two heads being operative during the pinching function and whilst the spaced cutting blades are deflected to produce a cut through the covering over the length of said section in the same plane as the axis of the wire, the pinching function being so performed as to distort the section of covering to permit the additional blade to cut through the covering without touching the wire itself.
 5. Apparatus as claimed in claim 4, in which a device is provided for peeling off the severed section of covering, said device comprising means enabling the wire to be drawn along a path involving an abrupt change of direction which is such as to allow the wire to emerge progressively outwards through the lengthwise cut in the section of covering.
 6. A method for the removal of a section of covering from an intermediate region of a wire covered with pliable plastics material in which the section of covering is severed circumferentially from the body of the wire-covering at two spaced locations by automatic cutting means and is severed lengthwise and thereafter the severed section is peeled off as by drawing the wire along a path involving an abrupt change of direction which is such as to allow the wire to emerge progressively outwards through the lengthwise severance in the section of covering. 